1. Field of the Invention
The present invention relates to the interconnection of optical waveguides, and more particularly to structures for coupling light frequency signals to a waveguide or between two waveguides.
2. Description of the Prior Art
U.S. Pat. No. 3,656,832 issued Apr. 18, 1972 to Judin, entitled MICRO-OPTICAL IMAGING APPARATUS, describes a high speed, diffraction limited point or line forming optical system utilizing uncorrected and imperfect single element lenses which are substantially spherical, hemispherical or cylindrical in shape, or appropriate index and size, in conjunction with radiation or light waves incident at limited divergence angles upon said lens elements; by virtue of small optical path differences of focusing exit rays, a diffraction predominant effect occurs.
U.S. Pat. No. 3,666,347 issued May 30, 1972 to Kitano et al, entitled SPHERICAL LENS STRUCTURES, describes a glass sphere containing thallium and sodium cations is immersed in a bath of a molten salt containing at least one kind of metal cations such as potassium cations to cause ion exchange through the glass-salt contact surface in a manner such that the concentrations of the cations, which constitute modifying oxides within the glass, vary from the center toward the outer surface of the sphere, which thereupon becomes a spherical lens.
U.S. Pat. No. 3,950,075 issued Apr. 13, 1976 to Cook et al, entitled LIGHT SOURCE FOR OPTICAL WAVEGUIDE BUNDLE, describes a source of optical wave energy for an optical communication system. One end of an optical waveguide fiber bundle is disposed in light-receiving relationship with respect to light from a Lambertian-type light source such as a light emitting diode. A spherical bead of transparent material disposed between the diode and the fiber bundle endface provides a rugged and inexpensive optical device that tends to collimate the light emitted from the diode.
U.S. Pat. No. 4,109,997 issued Aug. 29, 1978 to Iverson, entitled OPTICAL SLIP RINGS, discusses optical slip rings which permit signals to be transferred from a rotating body to a non-rotating body without any physical contact. Fiber optic bundles are utilized to conduct light signals on one body to separate fiber optic bundles on the other body. Light is projected across a small gap from the rotating bundle to the non-rotating bundle. Other variations use multiple channels, wave guides, derotating prisms and concentric annular mirrors to achieve signal transfer. The optical slip rings can transfer any signal which may be converted to a light signal.
U.S. Pat. No. 4,257,672 issued Mar. 24, 1981 to Balliet, entitled OPTICAL COUPLER FOR CONNECTING A LIGHT SOURCE TO AN OPTICAL TRANSMISSION LINE, describes an optical coupler for optically coupling an LED to an optical fiber includes a transparent spherical core. The index of refraction of the core is greater than of the spherical shell. A surface is formed on the opposite side of the coupler for coupling the optical fiber the optical coupler, and a cylinder is used to mount the optical coupler at a predetermined distance from the LED in an orientation maximizing the amount of light entering the optical fiber.
U.S. Pat. No. 4,548,464 issued Oct. 22, 1985 to Auracher et al, entitled FREQUENCY ANALYZER IN PLANAR WAVEGUIDE TECHNOLOGY AND METHOD OF MANUFACTURE, discloses a frequency analyzer which is manufactured in a planar waveguide technology, has a first substrate provided with a waveguide modulator for modulating light travelling in the waveguide connected to a lens for the Fourier transformation of the modulated light. The material of the lens is different than the material of the substrate having the modulator and preferably is either a rod shaped gradient lens or a second substrate, which has a geodesic waveguide lens pressed into the surface.
U.S. Pat. No. 4,097,117 issued June 27, 1987 to Neil et al, entitled OPTICAL COUPLER HAVING IMPROVED EFFICIENCY, describes a structure wherein the optical efficiency, with which a coupling portion of a fiber-optic can be coupled by evanescent fields to a planar optical waveguide through a phase-matching diffraction grating on the surface of the planar optical waveguide, is increased by deforming the coupling portion so that it is a negative replica of the undulating surface of the diffraction grating.
U.S. Pat. No. 4,304,461 issued Dec. 8, 1981 to Stewart et al, entitled OPTICAL FIBRE CONNECTORS, discloses an optical fiber connector comprising in respect of each of the optical fibers to be connected, a connector body part formed at one end with a recess which accurately locates a sphere lens relative to an optical fiber receiving hole extending through the body part and terminating at the center of the recess whereby the axis of the optical fiber received by the hole and preferably bonded to the surface of the sphere lens. Connecting means is provided for connecting together in axial alignment two of the body parts with the sphere lenses of the parts arranged in opposed relationship.
U.S. Pat. No. 4,371,233 issued Feb. 1, 1983 to Masuda, entitled LENS-APPLIED OPTICAL FIBER CONNECTOR, discloses a lens-applied optical fiber connector used to connect optical fibers for optical communication. The lens-applied optical fiber connector is structured so that the optical fiber connectors are inserted into a lens-applied sleeve and the sleeve is inserted into an adapter. In the present invention, the focal length of the lens is selected to be 0.09 to 0.27 mm and the lens is positioned at the point on the optical axis of the optical fiber apart from the end surface of the fiber as far as the focal length.
U.S. Pat. No. 4,712,854 issued Dec. 15, 1987 to Mikami, entitled OPTICAL WAVEGUIDE AND METHOD OF MAKING THE SAME, discloses a method of making an optical waveguide. First, ultraviolet light is radiated upon the surface of a transparent piece of photopolymerization material of a type whose refractive index is changed by the impact of ultraviolet light thereon, so that a refractive index profile in the depthwise direction of the piece of photopolymerization material is formed. Next, ultraviolet light is radiated upon the surface of the transparent piece of photopolymerization material in a pattern of a lengthwise extending stripe whose intensity is least in its central portion and becomes greater towards its edge portions, so that a refractive index profile in the widthwise direction of the piece of photopolymerization material is formed. Finally, an optical waveguide is structured from the thus irradiated piece of photopolymerization material. Optionally, these profiles may be parabolic profiles. Optionally, also, the structuring of the final optical waveguide may be done by laminating together two similar such pieces of photopolymerization material, thus treated, with their sides which were exposed to ultraviolet radiation, in contact with one another.
U.S. Pat. No. 4,796,969 issued Jan. 10, 1989 to Fantone, entitled FIBER OPTIC RELAY CONNECTOR, describes a fiber optic connector in the form of a two-element relay system which transforms and matches the numerical apertures of an entering beam to that of the acceptance numerical aperture of the exiting optic where in general the numerical apertures can be different. In preferred form, the connector is a pair of spherical balls with their surfaces in contact at a point along an optical axis extending through the centers of the balls. The radii of the spherical balls and their material composition are such that they operate to image fibers or the like one onto the other with their numerical apertures matched when each of the fibers are in optical contact with a respective one of the spherical balls at a point along the optical axis opposite the point of contact.
T. Baer, "Continuous wave laser oscillation in a Nd-YAG sphere", Optics Letters, Vol. 12 (6), pages 392-394, 1987 describes a dye laser whose output beam is coupled into a spherical laser for pumping.